Valve Flange Tightening Procedure
Proper flange tightening is critical for preventing leaks and ensuring system integrity. Follow these four essential steps for optimal results.
1
Initial Symmetrical Pre-Tightening
- Hand-tighten all flange bolts to ensure full contact with the flange surface
- Follow a symmetrical pattern during hand-tightening
- After turning one bolt, move to the bolt directly opposite it
- Prevents uneven compression of the gasket or warping of the flange
- Ensure every bolt is hand-tightened to a consistent degree
2
Gradual Torque Increase
- Use a torque wrench to apply force in incremental stages
- Start with a lower torque value that is a portion of the final required torque
- Maintain the same symmetrical sequence as the hand-tightening step
- Increase the torque in small, consistent increments with each pass
- Allows the gasket to compress slowly and settle into the flange joint
3
Cyclic Retightening
- After reaching initial target torque, perform multiple rounds of retightening
- Use the same symmetrical order as previous steps
- Bolts tightened earlier may loosen slightly as the gasket compresses
- Each cyclic pass helps balance the torque across all bolts
- Continue until no further adjustments are needed
4
Final Inspection and Verification
- Conduct a final check of each bolt's torque with a calibrated torque wrench
- Visually inspect the flange joint for any gaps or signs of gasket extrusion
- Perform a pressure test on the assembled valve and pipe system
- Absence of leakage confirms the tightening sequence was executed correctly
- Record the final torque values and inspection results for future reference
Key Considerations for Flange Tightening
Safety First
Always wear appropriate PPE and ensure the system is depressurized before beginning work.
Uniform Pressure
Maintain uniform pressure distribution across the flange to prevent leaks and damage.
Proper Tools
Use calibrated torque wrenches and appropriate tools for the specific flange size and type.
Documentation
Keep detailed records of torque values and inspections for maintenance and auditing purposes.
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